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• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/70—Carbohydrates; Sugars; Derivatives thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K38/00—Medicinal preparations containing peptides
  • A61K38/16—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
  • A61K38/43—Enzymes; Proenzymes; Derivatives thereof
  • A61K38/45—Transferases (2)
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
  • A61P31/12—Antivirals
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
  • A61P31/12—Antivirals
  • A61P31/14—Antivirals for RNA viruses
  • A61P31/18—Antivirals for RNA viruses for HIV
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
  • A61P31/12—Antivirals
  • A61P31/20—Antivirals for DNA viruses
  • A61P31/22—Antivirals for DNA viruses for herpes viruses

Definitions

• the present invention relates to new antiviral combinations for the treatment of prophylaxis of virus infections, especially viruses of the retrovirus or herpes groups.
• antiviral chemotherapeutic agents have been developed for clinical evaluation.
• a problem with the development of such agents is that, unlike bacteria, viruses are not free living organisms and are dependent for replication on the life processes of the host cell which they are infecting. It is therefore highly desirable for the antiviral agent to exert its effect specifically on the replicative processes of the virus rather than on the corresponding processes of normal (non-infected) cells.
• the antiviral agents so far developmed act via a variety of mechanisms to exert their antiviral effect, such mechanisms involving inhibition of different stages in the process of viral replication in the host cells.
• retroviral DNA involves the interactions of the enzyme reverse transcriptase (RNA dependent-DNA polymerase) with the constituent nucleotides (specifically desoxyribonucleotides) which act as building blocks for the new retroviral DNA.
• HIV Human Immunodeficiency Virus
• AIDS the causative virus of Acquired Immune Deficiency Syndrome
• DNA viruses such as herpes viruses
• the production of the new viral DNA involves the interaction of the enzyme DNA polymers with the constituent nucleotides (specifically desoxyribonucleotides) which act as building blocks for the new viral DNA.
• Antiviral action at this stage generally involves the metabolism of nucleotide analogues to "fraudulent" or deleterious nucleotides which mimic the normal physiological substrates and either compete for retroviral DNA polymerase (reverse transcriptase) or, in the case of DNA viruses, DNA polymerase or are incorporated into the viral DNA chain to render it non-functional.
• retroviral DNA polymerase reverse transcriptase
• nucleoside triphosphate derived from a nucleoside analogue which is converted by enzymes, firstly into the monophosphate and then subsequently into the diphosphate and finally into the triphosphate form.
• the conversion of the nucleoside analogue to its monophosphate is effected by a thymidine kinase which may be a normal cellular enzyme (i.e. present in uninfected cells) or a virally specified enzyme, depending upon the nucleoside analogue and the infecting virus.
• zidovudine (3′-azido-3′-deoxythymidine) which is related to the naturally occurring nucleoside, thymidine, but which contains an azido groups (N3), rather than hydroxy (OH) in the 3′-position of the sugar moiety.
• Zidovudine is converted sequentially to its mono-, di- and triphosphate forms by normal cellular enzymes.
• the 5′-triphosphate of zidovudine serves as an inhibitor of reverse transcriptase since it resembles the natural nucleotide substrate, deoxythymidine 5′-triphosphate (dTTp), and as a result competes with dTTP for binding to the reverse transcriptase.
• zidovudine acts as a substrate for reverse transcriptase, it becomes incorporated into the viral DNA chain but, since it contains an azido group rather than the normal hydroxyl group at the 3′-position of the sugar moiety, it is believed to act as a DNA chain terminator whereby viral replication is prevented.
• zidovudine and related compounds which operate via an analogous mode of action, involves competitive inhibition of the virus-coded reverse transcriptase and/or premature chain termination of the viral DNA chain.
• acyclovir i.e. 9-[(2-hydroxyethoxy)methyl]guanine
• the antiviral mechanisms of action of acyclovir involves first its permeation of the cell membrane and then its conversion to acyclovir monophosphate by the virally specified enzyme thymidine kinase. Once formed, acyclovir monophosphate is converted by normal cellular enzymes (kinases) to the diphosphate and subsequently to acyclovir triphosphate (ACVTP).
• kinases normal cellular enzymes
• Acyclovir triphosphate serves as an inhibitor of viral DNA polymerase since it resembles the natural nucleotide substrate, deoxyguanosine triphosphate (dGTP), and as a result competes with dGTP for binding to the DNA polymerase and thus competively inhibits the effectiveness of the enzyme and consequently viral replication.
• dGTP deoxyguanosine triphosphate
• the antiviral effect of acyclovir, and related compounds which operate via an analogous mode of action involves competitive inhibition, premature chain termination and apparent inactivation of the viral DNA polymerase.
• a disadvantageous aspect of a nucleoside analogue is that the naturally occurring substrate for the relevant enzyme may compete at one or more of the enzymatic steps involved in the metabolism of the analogue to its biologically active form or may antagonize the effect of the active metabolite. In this manner, the build up of, for example, dTTP may hinder the binding of zidovudine 5′-triphosphate to the polymerase and thereby prevent the subsequent termination of viral DNA processing.
• thymidine may compete with zidovudine for phosphorylation of thymidine kinase and may, therefore, reduce the cellular formation of one of the intermediate metabolites (zidovudine 5′-monophosphate) required for the final active metabolite (zidovudine 5-triphosphate) and this nucleoside analogue.
• the buildup of, for example, thymidine may hinder the binding of acyclovir to the virally specified thymidine kinase and thereby antagonise the subsequent phosphorylation of acyclovir, which posphorylation has been shown to be an essential step for the antiviral action of this drug.
• thymidine phosphorylase in conjunction with an antiviral agent of the above described type i.e. a nucleoside which is phosphorylated to the monophosphate by a thymidine kinase, gives a surpisingly large potentiation of the antiviral activity of the antiviral agent.
• an antiviral agent of the above described type i.e. a nucleoside which is phosphorylated to the monophosphate by a thymidine kinase
• thymidine phosphorylase in combination with an antiviral agent of the above described type results in a surprising synergistic increase in antiviral efficacy in comparison with the individual antiviral effects of the components of the combination. Indeed, thymidine phosphorylase may exhibit no antiviral effect whatsoever.
• the present invention has been found to be particularly applicable to the treatment of asymptomatic infections or disease caused by or associated with human retroviruses, as described below.
• a combination of (a) an antiviral compound which is dependent upon enzymatic phosphorylation for conversion in vivo to an inhibitor of, and/or an alternative substrate for a viral DNA-polymerase and (b) a thymidine phosphorylase, components (a) and (b) of the combination being employed in a ratio whereby a synergistic antiviral effect is achieved.
• herpes virus infections especially herpes simplex, varicella zoster, cytomegalo-virus (CMV) and Epstein-Barr virus (EBV) infections.
• CMV cytomegalo-virus
• EBV Epstein-Barr virus
• the compounds according to the invention are especially useful for the treatment or prophylaxis of AIDS and relates clinical conditions such as AIDS-related complex (ARC), progressive generalised lymphadenopathy (PGL), AIDS-related neurological conditions, such as multiple sclerosis or tropical paraparesis, anti-HIV antibody-positive and HIV-positive conditions, Kaposi's sarcoma and thrombocytopenia purpura.
• the compounds may also be used in the treatment or prevention of psoriasis.
• the antiviral compound and the thymidine phosphorylase may be administered substantially simultaneously for example in separate formulations, or sequentially, preferably by different routes. In the latter case, however, the components of the combination are administered within a sufficiently short interval to ensure that a synergistic antiviral effect is achieved.
• the present invention also provides a method of potentiating in a mammal having a viral infection the antiviral activity of an antiviral compound being administered to said mammal and which depends on a thymidine kinase for conversion to a deleterious substrate and/or inhibitor of a viral DNA polymerase, which comprises administering to said mammal an effective, non-toxic potentiating amount of a thymidine phosphorylase simultaneously with, previous to or subsequent to the administration of the antiviral compound.
• An advantage of the combination according to the invention is that it enables one to obtain an improved antiviral efficacy at a particular dosage of the antiviral compound (compared with the compound used alone) thereby improving the therapeutic index of the compound.
• the combination may be used to treat conditions which would otherwise require relatively large dosages of the antiviral compound at which the toxicity problems may occur.
• the smaller dosages of the combination may provide for increased convenience to the patient and increased compliance.
• this is generally selected from compounds that are enzymatically phosphorylated by a thymidine kinase in vivo to give a nucelotide which is an inhibitor of the viral DNA-polymerase and/or is incorporated into the viral DNA chain to make it non-functional.
• Such compounds are generally substrates for an appropriate kinase enzyme which phosphorylates the compounds to form initially a monophosphate which is then phosphorylated (also by kinase enzymes) first to the diphosphate and finally to the triphosphate which interacts deleteriously with the DNA-polymerase.
• the antiviral compound employed in the combinations according to the invention may be selected, particularly for the treatment of prophylaxis of herpes infections, for example, from acyclovir and analogues thereof, e.g., those compounds of formula (wherein X is hydrogen or sulphur, R is hydrogen, hydroxy or amino and Y is hydrogen or hydroxymethyl) and physiologically acceptable salts and esters thereof.
• examples or preferred compounds of formula (I) for use in accordance with the present invention include 9-[[(2-hydroxy-1-(hydroxymethyl)ethoxy]methyl]guanine as well as prodrugs that are converted in vivo in to the above compounds, e.g. 2-amino-9-[(2-hydroxyethoxy)methyl]adenine and 9-[[2-hydroxy-1-­(hydroxymethyl)ethoxy]methyl]-2,6-diaminopurine.
• antiviral compounds can be obtained by processes that are described in the literature for example, U.K. Patent Specifications 1523865 and 2104070A, and European Patent Specification No. 108285.
• the antiviral compound employed in the combinations according to the invention may also be selected, particularly for the treatment of prophylaxis or retroviral infections, for example, from zidovudine and analogues thereof, e.g., those compounds of formula (II). in which X represents an oxygen or sulphur atom and pharmaceutically acceptable derivatives thereof including esters and salts and other compounds that are bioprecursors of the compounds of formula (III) or are capable of hydrolysis thereto.
• zidovudine i.e. the compound of formula (II) in which the 3′-azido group is in the erythro configuration and X represents an oxygen atom
• zidovudine i.e. the compound of formula (II) in which the 3′-azido group is in the erythro configuration and X represents an oxygen atom
• zidovudine i.e. the compound of formula (II) in which the 3′-azido group is in the erythro configuration and X represents an oxygen
• esters of the compounds of formulae (I) and (II) include acyl esters such as straight or branched chain acyl (e.g., C2 ⁇ 18), aracyl (e.g., phenylacetyl), aroyl (e.g., benzoyl optionally substituted by halogen, C1 ⁇ 4 alkyl or C1 ⁇ 4 alkoxy), organosulphonyl (e.g., methanesulphonyl) and mono-, di- or triphosphate esters as well as the corresponding thio esters including dithiocarbamyl, e.g., dialkyl (e.g., methyl) dithiocarbamoyl, esters.
• acyl esters such as straight or branched chain acyl (e.g., C2 ⁇ 18), aracyl (e.g., phenylacetyl), aroyl (e.g., benzoyl optionally substituted by halogen,
• Examples of pharmaceutically acceptable salts of the compounds of formulae (I) and (II) include base salts, e.g., derived from an appropriate base, such as alkali metal (e.g. sodium) or alkaline earth metal salts.
• base salts e.g., derived from an appropriate base, such as alkali metal (e.g. sodium) or alkaline earth metal salts.
• the compounds of formula (II) and their derivatives may be prepared in conventional manner for example as described in the following references or by methods analogous thereto, J.R. Horwitz et al ., J. Org. Chem., 29 , (July 1984) 2076-78, and M. Imazawa et al ., J. Org Chem., 43 , (15) (1978) 3044-3048; K.A. Watanabe et al ., J. Org. Chem., 45 , 3274, (1980); or R.P. Glinski et al ., J. Chem. Soc., Chem. Commun., 915 , (1970) and also European Patent Specification No. 196185.
• the thymidine phosphorylase for use in accordance with the present invention is preferably of bacterial origin.
• the production and purification of such thymidine phosphorylase is described in U.S. patents 4,097,337 and 4,178,212, both of which are incorporated herein by reference.
• the present invention further includes a process for preparing the above-defined combinations according to the invention which comprises bringing into association an above-defined antiviral compound and thymidine phosphorylase to provide a synergistic antiviral effect.
• the combinations according to the invention may be administered to the subject concerned in conventional manner.
• the antiviral compound and the thymidine phosphorylase may be administered simultaneously (e.g., in a unitary pharmaceutical formulation) or separately (e.g., in separate pharmaceutical formulations).
• the respective components of the combinations may be administered by the topical, oral, rectal or parenteral (e.g. intravenous, subcutaneous or intramuscular) route.
• the dosage of the combination will depend on the condition being treated, the particular antiviral agent and other clinical factors such as the weight and condition of the patient and the route of administration of the compound.
• a dosage of antiviral compound of 1 to 100 mg/kg/day, preferably 2 to 30 mg/kg/day is generally sufficient.
• the amount of thymidine phosphorylase in the combination is preferably in the range of about 0.1 to 100 units of enzyme activity per kilogram of body weight per day and particularly in the range of about 1 to 20 units of enzyme activity per kilogram of body weight per day.
• the ratios of the antiviral compound to the thymidine phosphorylase in terms of mg: units of enzyme activity for use according to this invention is from 1:100 to 100:0.1, preferably from 1:20 to 60:1.
• the formulations include those suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal or parenteral (including subcutaneous, intramuscular, intravenous, intradermal, intrathecal and epidural) administration.
• the formulations may conveniently be presented in unit dosage form and may be prepared by conventional pharmaceutical techniques. Such techniques include the step of bringing into association the active ingredients with the pharmaceutical carrier(s) or excipient(s). In general, the formulations are prepared by uniformly and intimately bringing into association the active ingredients with liquid carriers or finely divided solid carriers of both, and then, if necessary, shaping the product.
• Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing predetermined amounts of the active ingredients; as powders or granules; as solutions or suspension in an aqueous liquid or a non-aqueous liquid; or as oil-in-water emulsions or a water-in-oil emulsions.
• a tablet may be made by compression or moulding, optionally with one or more accessory ingredients.
• Compressed tablets may be prepared by compressing in a suitable machine the active ingredients in a free-flowing form such as a powder or granules, optionally mixed with a binder, lubricant, inert diluent, preservative, surface active or dispersing agent.
• Moulded tablets may be made by moulding in a suitable machine a mixture of the powdered compound moistened with an inert liquid diluent.
• the tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled release of the active ingredient therein.
• the formulations are preferably applied as a topical ointment or cream containing the antiviral active ingredient in an amount of, for example. 0.075 to 20% w/w, preferably 0.2 to 15% w/w and most preferably 0.5 to 10% w/w.
• the active ingredients may be employed with either paraffinic or a water-miscible ointment base.
• the active ingredients also may be formulated in a cream with an oil-in-water cream base.
• the thymidine phosphorylase may be administered topically while the antiviral agent is administered separately by another route (e.g., orally, rectally, intraveneously, subcutaneously or intramuscularly).
• the aqueous phase of the cream base may include, for example, at least 30% w/w of the polyhydric alcohol, i.e. an alcohol having two or more hydroxyl groups such as propylene glycol, butan-1,3-diol, mannitol, sorbitol, glycerol and polyethylene glycol and mixtures thereof.
• the topical formulation may desirably include a compound which enhances absorption or penetration of the active ingredient through the skin or other affected areas. Examples of such dermal penetration enhancers include dimethylsulphoxide and related analogues.
• the oil phase of the emulsions of this invention may be constituted form known ingredients in a known-manner. While the phase may comprise merely an emulsifier, it desirably comprises a mixture of at least one emulsifier with a fat or an oil or with both a fat and an oil. Preferably, a hydrophilic emulsifier is included together with a lipophilic emulsifier which acts as a stabilizer. It is also preferred to include both an oil and a fat.
• the emulsifier(s) with or without stabilizer(s) make up to so-called emulsifying wax, and the wax together with the oil and/or fat make up the so-called emulsifying ointment base which forms the oily dispersed phase of the creams formulations.
• Emulsifiers and emulsion stabilizers suitable for use in the formulations of the present invention include Tween 60, Span 80, cetostearyl alcohol, myristyl alcohol, glycerol mono-stearate and sodium lauryl sulphate.
• Formulations suitable for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffersm bacteriostats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions which may include suspending agents and thickening agents.
• the formulations may be presented in unit-dose or multi-dose containers, for example, sealed ampoules and vial, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example, water for injections, immediately prior to use.
• Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.
• Preferred unit dosage formulations are those containing a daily dose or unit daily sub-dose, as herein above recited, or an appropriate fraction thereof, of the active ingredients.
• formulations of this invention may include other agents conventional in the art having regard to the type of formulation in question, for example, those suitable for oral administration may include flavouring agents.
• the enhancement of the Anti-Friend Leukemia Virus (FLV) activity of zidovudine by bacterial thymidine phosphorylase is shown in Table 1.
• FG-10 cells were used seeded on a plate one day before they were infected with FLV. One hour after infecting, known concentrations of the test compound or combination were added. The plates were incubated for 3 days, the media replaced with fresh McCoy's 5A media and incubated another 3 days. Concentrations of test compound/combinations giving 50% inhibition of plaques (IC50 nM) were determined as shown in Table 1.
• Antiviral activity was determined using a plaque reduction assay. Petri plates were seeded with Vero cells which were then allowed to grow to confluency. Each plate was then infected with a fixed number of plaque forming units (abut 100-500) of herpes simplex type 1 (KOS strain). The inhibitors, either alone or in the indicated combinations, were dissolved to give the indicated concentration in minimal essential medium containing 2% heat inactivated fetal calf serum and 0.5% human immune serum globulin: One hour after infection the solutions (10 ml per plate) were added to the cultures. Three days later the cultures were formalin-fixed and stained with crystal violet, and the plaques were counted.
• KOS strain herpes simplex type 1
• the antiviral compound is zidovudine or acyclovir.
• the active compounds are dissolved in a mixture of purified water and glycerol and heated to 70°C. The remaining ingredients are heated together at 70°C. The two parts are added together and emulsified. The mixture is cooled and filled into containers.

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• 1988
  • 1988-04-22 AT AT88303651T patent/ATE72122T1/de not_active IP Right Cessation
  • 1988-04-22 EP EP88303651A patent/EP0289229B1/fr not_active Expired - Lifetime
  • 1988-04-22 JP JP63100016A patent/JPS63280026A/ja active Pending
  • 1988-04-22 DE DE8888303651T patent/DE3868125D1/de not_active Expired - Fee Related

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